1. Field of the Invention
The present invention relates to a hand operated label printing machine or a hand labeler and particularly to a constant pressure printing mechanism and an ink supply mechanism for use with a hand labeler.
In a hand labeler, a series of pressure sensitive labels, which are temporarily adhered to a strip of carrier paper, are incrementally fed onto a printing platen in response to the squeezing of an actuating lever, so that the labels may be imprinted with selected indicia. The printed labels are peeled one by one from the carrier paper and are adhered to a commodity.
2. Description of the Prior Art
In one form of a conventional constant pressure printing mechanism for a hand labeler, a printing head is carried on the leading end of a printing lever, which may be integral with a hand operated lever, so that the printing head is moved together with the printing lever down toward the printing platen by the squeezing operation of the hand lever, thus printing the labels which have been fed onto the platen.
In such a conventional hand labeler, however, the printing pressure of the labels is directly dependent upon the strength and duration of the squeezing force that has been applied to the hand lever, with the resultant disadvantage that the density of the imprints differs among the labels in accordance with the intensity of the squeezing force.
To eliminate this problem, one constant pressure printing mechanism is shown in U.S. Pat. No. 3,911,817. In the constant pressure printing mechanism disclosed therein, a compression spring is interposed between the hand operated lever and the printing lever, which levers are made separate from each other rather than being integrated. An ink applying device, which is biased for rotation by a return spring, is provided at a front portion of the hand labeler and the ink applying device is urged into abutment contact with the types of the printing head. When the hand lever is squeezed, the aforementioned compression spring is compressed to store a compression force. When the stored compression force exceeds or overcomes the restraining limit of the return spring of the ink applying device, then the printing lever and the printing head are urged down to the platen, while also pushing away the ink applying device, by the force of the compression spring. Printing of the labels upon the platen is thus effected. As a result, the label printing is accomplished only by the stored force of the compression spring, irrespective of the intensity of the lever squeezing force, so that the printing operation can always be performed under a preset constant pressure. This has the advantage that the imprints on the labels can be less irregular.
In the above-described constant pressure printing mechanism, however, the printing is caused solely by the elastic force of the compression spring which is coactive with the printing lever. As the number of labels imprinted increases, the resultant printing pressure is reduced in proportion to the gradual weakening of the compression spring. Therefore, this conventional printing mechanism cannot be free from the disadvantage that the desired clear prints of the labels with preset density cannot be expected after many labels have been imprinted.
In other constant printing pressure mechanisms, it is known to have a pressure applying assembly on one relatively moving element of the hand labeler apply pressure to and eventually override a pressure receiving assembly on another relatively moving element of the hand labeler. This engagement between assemblies stops the hand operated lever or operating lever of the labeler from being operated to cause label imprinting until after a predetermined squeezing force is applied to the hand lever. Once the assemblies override each other, then the types on the printing head imprint a label with a constant printing pressure. Examples of this can be found in my copending applications, Ser. No. 866,991, filed Jan. 5, 1978 (now U.S. Pat. No. 4,207,816) and Ser. No. 909,431, filed May 25, 1978 (now U.S. Pat. No. 4,206,704). However, it is desired to make these assemblies simpler and more efficient than those in the above-mentioned applications.
Also in a hand labeler, inking of the types that imprint the label strips should be accomplished with a predetermined inking pressure, using inking rollers that follow a predetermined pathway across the faces of the types being inked, and wherein the mechanism by which the inking is accomplished operates efficiently and effectively and does not protrude so far beyond the front of the hand labeler as to interfere with a view of the label being applied by the hand labeler at the front of the body of the hand labeler. Various inking assemblies have been devised, including my own U.S. application Ser. No. 830,806, filed Sept. 6, 1977 (now U.S. Pat. No. 4,213,389). Again, however, the simplicity of the inking means for accomplishing the above noted purposes and further for assuring that the inking mechanism does not protrude in front of the labeler body is not as great as possible.